Mystery Stain..............

Comm Olefin.. Clear chair mat was over that stain.. I thought it might be the petroleum oils they use to make those mats that seeped into the carpet.. But if that was true it should of covered the whole area of the mat........................................................

Tried de-sov-all solvent...rust remover.. I know it wasn't coffee stain but gave that a try... Stain didn't fade at all..........................................

I Never saw the clear floor mat.. Don't know what was on the bottom of the mat....

ANY THOUGHTS.... Maybe a patch job??????????

It's interesting to see that the pattern is almost exactly where the chair casters would roll - I think NR could be right however I have another theory.

The pressure from the wheels may have has caused a wicking from something under the carpet on the floor.   This looks like a job for PadMan.

I would clean with a olefin prespray boosted with a Citrus solvent and a powdered peroxide. Then pad it out with cotton pads. Then see if there is still transfer on the cotton pads. Take it from there.

Then consider citric acid.

That looks like a stain from down under...most likely before the desk mat was put there.... I find in a lot of commercial buildings the office gets moved around and most times before the carpet is layed the concrete isn't power washed.

Thats why I hate commercial to many mystery stains

Personally I hate commercial... so it could rock all it wants

John

 First clean as you would normally then try acetic acid boosted with a small amount of citric acid (circa 6 - 9ml/pint)  the removal effect develops over the drying period.

 If that doesnt work as a last resort try sodium metabisulphite.